1. Technical Field
The present invention relates to a printing apparatus that performs printing on a print medium by causing a discharge head to perform scanning movement and, in particular to, a technique that optically detects displacement of a discharge head.
2. Related Art
For example, in a printing apparatus such as an ink jet printer that performs printing on a print medium by discharging ink from a discharge head that performs scanning movement with respect to the print medium, an optical detection means may be used to detect displacement of the discharge head. For example, in a technique described in JP-A-2010-188532 (for example, FIG. 3), a displacement of a carriage is detected by a linear encoder in which a scale fixed to a printing apparatus and an optical sensor attached to a carriage are combined. In such a printing apparatus, there is a problem that a detection sensitivity of position or displacement gradually degrades due to adhesion of ink mist flying from a discharge head.
For this problem, the technique described in JP-A-2010-188532 estimates a timing at which the service life of an encoder expires by associating an occurrence frequency of false detection with an integrated amount of used ink and notifies a user of the service life and/or sends warning to a user as needed.
A use mode of the printing apparatus as described above varies depending on each user, so that the service life estimation described above may not function appropriately in some cases. For example, in order to reduce the possibility that the discharge head comes into contact with a print medium during printing and an error occurs, the printing may be performed in a state in which a gap between the discharge head and the print medium is larger than an appropriate value. In such a case, generation of mist is larger than that during printing using an appropriate gap, so that staining in the apparatus progresses faster than estimation obtained from the amount of used ink. In the related art described above, it is not possible to handle such a problem and it is difficult to appropriately perform the service life management of the detection means.